The 34-year-old took to social media on Saturday to announce the news.
The St. Louis Rams selected Long with the second overall pick in the 2009 NFL Draft. After spending his first eight NFL seasons with the Rams, Long joined the New England Patriots for one campaign before spending his final two seasons with the Eagles.
Long, a native of Santa Monica, Calif., was at his statistical best from 2010-13 in St. Louis, recording at least 8.5 sacks in each of those four seasons.
He captured back-to-back Super Bowls in 2016 (with the Patriots) and 2017 (with the Eagles) and was named the 2018 Walter Payton Man of the Year for his extensive charity work and community service.
The Eagles will be left with a hole in their front seven, though they could look to their talented prospect pool to help fill the void.